Early psychosocial stress (e.g., parental divorce, abuse) is conjectured to place individuals on a developmental trajectory leading to earlier initiation of sexual activity, earlier reproduction, and having more sex partners than those with less early psychosocial stress. But does it also affect an individual’s mate choice? The present study examined whether early psychosocial stress affects preferences and dislikes for opposite-sex faces varying in masculinity/femininity, a putative indicator of mate quality, in premenopausal women (58 with a natural cycle, 53 pill-users) and (...) 196 men. No significant three-way interactions were found when women selected the most or least preferred face with participant group (natural cycle, pill), conception risk (low, high), and early psychosocial stress (low, high) as between-subjects factors. Early psychosocial stress did not affect men’s face preferences when selecting the most preferred face. However, men with high early psychosocial stress disliked masculine faces significantly more so than men with low early psychosocial stress. Overall it was concluded that early psychosocial stress does not affect mate choice with the exception that men with high early psychosocial stress were more likely to dislike masculine female faces. It was suggested that men with high early psychosocial stress may dislike masculine female faces because they have nothing to gain from associating with women with such faces. (shrink)

Life history data, attractiveness ratings of male photographs, and attitudes towards partnership and child-rearing of 321 women were used to test four evolutionary models (quantitative reproductive strategy, male short-age, polygyny indication, and maternal reproductive interests) which attempt to explain the influence of family composition on reproductive strategies. Links between early menarche and other markers of reproductive strategy were investigated. Childhood stress and absence of a father figure, whether genetically related or not, were found to have accelerated menarche whereas having younger (...) siblings decelerated it. Early menarche was associated with attractiveness ratings, the number of partners desired for the immediate future, and the early onset of intimate relationships. It was not linked with sociosexual orientation, mate choice criteria, and investment in the subjects’ own children, but these three markers were interrelated. The implications of the findings for the four evolutionary models are discussed. (shrink)

Household structure may have strong effects on reproduction. This study uses household demographic data for 59 women in a Caribbean village to test evolutionary hypotheses concerning variation in reproductive strategies. Father-absence during childhood, current household composition, and household economic status are predicted to influence age at first birth, number of mates, reproductive success, and pair-bond stability. Criterion variables did not associate in a manner indicative of r- and K-strategies. Father-absence in early childhood had little influence on subsequent reproduction. Household wealth (...) and alloparenting were positively associated with age at first birth. Alloparenting was negatively associated with reproductive success. Women in long-term conjugal unions had higher reproductive success than did single women. Number of adult male kin resident in the household was negatively associated with women’s number of mates. (shrink)

The aim of this study is an analysis of the possible adaptive consequences of delivery of low birth weight infants. We attempt to reveal the cost and benefit components of bearing small children, estimate the chance of the infants’ survival, and calculate the mothers’ reproductive success. According to life-history theory, under certain circumstances mothers can enhance their lifetime fitness by lowering the rate of investment in an infant and/or enhancing the rate of subsequent births. We assume that living in a (...) risky environment and giving birth to a small infant may involve a shift from qualitative to quantitative production of offspring. Given high infant mortality rates, parents will have a reproductive interest in producing a relatively large number of children with a smaller amount of prenatal investment. This hypothesis was tested among 650 Gypsy and 717 non-Gypsy Hungarian mothers. Our study has revealed that 23.8% of the Gypsy mothers had low birth weight (<2,500 g) children, whose mortality rate is very high. These mothers also had more spontaneous abortions and stillbirths than those with normal weight children. As a possible response to these reproductive failures, they shortened birth spacing, gaining 2–4 years across their reproductive lifespan for having additional children. Because of the relatively short interbirth intervals, by the end of their fertility period, Gypsy mothers with one or two low birth weight infants have significantly more children than their ethnic Hungarian counterparts. They appear to compensate for handicaps associated with low birth weights by having a larger number of closely spaced children following the birth of one or more infants with a reduced probability of survival. The possible alternative explanations are discussed, and the long-term reproductive benefits are estimated for both ethnic groups. (shrink)

Tomasello's moral psychology of obligation would be developmentally deepened by greater attention to early experiences of cooperation and shared social agency between parents and infants, evolved to promote infant survival. They provide a foundation for developing understanding of the mutual obligations of close relationships that contribute (alongside peer experiences) to growing collaborative skills, fairness expectations, and fidelity to social norms.

We examine the relationship between birth order and reproductive behaviors in a sample of Australian residents, accounting for personality, personal achievements, and family structure. Using generalized linear models and survival analyses we build predictive models for each reproductive measure and test those models on an independent data subset. Compared with functional firstborns (middle-borns more than 5 years younger than their next older sibling), male middle-borns and last-born females had younger ages of first sexual intercourse, and middle-born females had a younger (...) age at first pregnancy. There was no difference in females’ age at first birth. Male middle-borns tended to have an older average age at first birth. Controlling for age, both male and female middle-borns had fewer children. Overall, middle-borns differ more from functional firstborns than do last-borns. Given the significant but small effect sizes demonstrated in this study, we suggest that developmental characteristics that may facilitate middle-borns’ success within the natal family carry slight fitness costs during the reproductive years. (shrink)

Extrinsic mortality is a key influence on organisms’ life history strategies, especially on age at maturity. This historical longitudinal study of 125 women in rural Domenica examines effects of extrinsic mortality on human age at maturity and pace of reproduction. Extrinsic mortality is indicated by local population infant mortality rates during infancy and at maturity between the years 1925 and 2000. Extrinsic mortality shows effects on age at first birth and pace of reproduction among these women. Parish death records show (...) huge historical variation in age-specific mortality rates. The infant mortality rate (IMR) in the early 1920s was low, increased dramatically beginning in 1929, and reached a maximum in the 1950s, at which point IMR declined steadily to its present low rate. The mortality rate early in life showed a quadratic association with age at first birth. Women who experienced conditions of low IMR early in life reproduced relatively late in life. Those born into moderately high levels of infant mortality tended to reproduce earlier than those born at low levels. At very high infant mortality levels early in life, women went on to delay reproduction until relatively late, possibly as a result of somatic depletion and energetic stress associated with the conditions that lead to high IMR. Population mortality rates at age of maturity also showed a quadratic association with age at first birth. The pace of reproduction, estimated as number of surviving offspring controlled for maternal age, showed a similar quadratic effect. There were complex interactions between population mortality rates in infancy and at maturity. When extrinsic mortality was high during infancy, extrinsic mortality later in life had little effect on timing of first birth. When extrinsic mortality was low to moderate in infancy, extrinsic mortality later in life had significant effects on adult reproduction. I speculate that these effects are mediated through development of personality facets associated with reproduction. (shrink)

Life history theory suggests that in risky and uncertain environments the optimal reproductive strategy is to reproduce early in order to maximize the probability of leaving any descendants at all. The fact that early menarche facilitates early reproduction provides an adaptationist rationale for our first two hypotheses: that women who experience more risky and uncertain environments early in life would have (1) earlier menarche and (2) earlier first births than women who experience less stress at an early age. Attachment theory (...) and research provide the rationale for our second two hypotheses: that the subjective early experience of risky and uncertain environments (insecurity) is (3) part of an evolved mechanism for entraining alternative reproductive strategies contingent on environmental risk and uncertainty and (4) reflected in expected lifespan. Evidence from our pilot study of 100 women attending antenatal clinics at a large metropolitan hospital is consistent with all four hypotheses: Women reporting more troubled family relations early in life had earlier menarche, earlier first birth, were more likely to identify with insecure adult attachment styles, and expected shorter lifespans. Multivariate analyses show that early stress directly affected age at menarche and first birth, affected adult attachment in interaction with expected lifespan, but had no effect on expected lifespan, where its original effect was taken over by interactions between age at menarche and adult attachment as well as age at first birth and adult attachment. We discuss our results in terms of the need to combine evolutionary and developmental perspectives and the relation between early stress in general and father absence in particular. (shrink)

This paper examines the effects of three different types of father absence on the timing of life history events among women in rural Bangladesh. Age at marriage and age at first birth are compared across women who experienced different father presence/absence conditions as children. Survival analyses show that daughters of fathers who divorced their mothers or deserted their families have consistently younger ages at marriage and first birth than other women. In contrast, daughters whose fathers were labor migrants have consistently (...) older ages at marriage and first birth. Daughters whose fathers died when they were children show older ages at marriage and first birth than women with divorced/deserted fathers and women with fathers present. These effects may be mediated by high socioeconomic status and high levels of parental investment among the children of labor migrants, and a combination of low investment, high psychosocial stress, and low alloparental investment among women with divorced/deserted fathers. Our findings are most consistent with the Child Development Theory model of female life history strategies, though the Paternal Investment and Psychosocial Acceleration models also help explain differences between women in low paternal investment situations (e.g., father divorced/abandoned vs. father dead). Father absence in and of itself seems to have little effect on the life history strategies of Bangladeshi women once key reasons for or correlates of absence are controlled, and none of the models is a good predictor of why women with deceased fathers have delayed life histories compared with women whose fathers are present. (shrink)

Benefits to females of short-term mating have recently been identified, and it has been suggested that women have evolved adaptations for this strategy. One piece of evidence supporting such a female adaptation would be that women find the experience of a one-night stand as affectively positive as men. Individuals (N = 1,743) who had experienced a one-night stand were asked to rate aspects of their “morning after” feelings (six positive and six negative). Women were significantly more negative and less positive (...) than men. Although women did not especially view these relationships as a prelude to long-term relationships, they felt greater regret than men about having been “used.” Extra-pair copulations were rated more negatively, but not less positively, than singles’ experiences. There was no interaction between gender and mated status on positivity or negativity. Although, in terms of subsequent affective response, women do not seem well adapted to casual sexual encounters, it may be important to distinguish impelling sexual motivation preceding intercourse from later evaluations of the event. Menstrual cycle changes may also be important in altering the strength and target of sexual motivation. (shrink)

We add to Archer's review with mention of sexual orientation differences in aggression and empathy, which suggest a biological basis for the mediating role of empathy. We also note that Archer's view of sex differences will illuminate discussion of conduct disorder, which can only be of help to researchers in this field.

I argue that the magnitude and nature of sex differences in aggression, their development, causation, and variability, can be better explained by sexual selection than by the alternative biosocial version of social role theory. Thus, sex differences in physical aggression increase with the degree of risk, occur early in life, peak in young adulthood, and are likely to be mediated by greater male impulsiveness, and greater female fear of physical danger. Male variability in physical aggression is consistent with an alternative (...) life history perspective, and context-dependent variability with responses to reproductive competition, although some variability follows the internal and external influences of social roles. Other sex differences, in variance in reproductive output, threat displays, size and strength, maturation rates, and mortality and conception rates, all indicate that male aggression is part of a sexually selected adaptive complex. Physical aggression between partners can be explained using different evolutionary principles, arising from the conflicts of interest between males and females entering a reproductive alliance, combined with variability following differences in societal gender roles. In this case, social roles are particularly important since they enable both the relatively equality in physical aggression between partners from Western nations, and the considerable cross-national variability, to be explained. (shrink)

Worldwide there are substantial differences within and between countries in aggression and violence. Although there are various exceptions, a general rule is that aggression and violence increase as one moves closer to the equator, which suggests the important role of climate differences. While this pattern is robust, theoretical explanations for these large differences in aggression and violence within countries and around the world are lacking. Most extant explanations focus on the influence of average temperature as a factor that triggers aggression, (...) or the notion that warm temperature allows for more social interaction situations in which aggression is likely to unfold. We propose a new model, CLimate, Aggression, and Self-control in Humans, that helps us to understand differences within and between countries in aggression and violence in terms of differences in climate. Lower temperatures, and especially larger degrees of seasonal variation in climate, call for individuals and groups to adopt a slower life history strategy, a greater focus on the future, and a stronger focus on self-control. The CLASH model further outlines that slow life strategy, future orientation, and strong self-control are important determinants of inhibiting aggression and violence. We also discuss how CLASH differs from other recently developed models that emphasize climate differences for understanding conflict. We conclude by discussing the theoretical and societal importance of climate in shaping individual and societal differences in aggression and violence. (shrink)

Following from life history and attachment theory, individuals are predicted to be sensitive to variation in environmental conditions such that risk and uncertainty are internalized by cognitive, affective, and psychobiological mechanisms. In turn, internalizing of environmental uncertainty is expected to be associated with attitudes toward risk behaviors and investments in education. Native American youth aged 10–19 years (n = 89) from reservation communities participated in a study examining this pathway. Measures included family environmental risk and uncertainty, present and future time (...) perspective, adolescent attachment, attitudes toward risk, investments in education, and salivary cortisol. Results support the idea that environmental risk and uncertainty are internalized during development. In addition, internalizing mechanisms significantly predicted attitudes toward risk and education: (1) lower scores on future time perspective and higher cortisol predicted higher scores on risk attitudes, and (2) higher scores on future time perspective and lower scores on problems with attachment predicted higher self-reported school performance. Gender differences were seen, with males anticipating a shorter lifespan than females, which predicted higher scores on risk attitudes and lower school performance. Implications for research on adolescent problem behavior and academic achievement are discussed. (shrink)

The fast–slow paradigm of life history focuses on how individuals grow, mate, and reproduce at different paces. This paradigm can contribute substantially to the field of personality and individual differences provided that it is more strictly based on evolutionary biology than it has been so far. Our study tested the existence of a fast–slow continuum underlying indicators of reproductive effort—offspring output, age at first reproduction, number and stability of sexual partners—in 1,043 outpatients with healthy to severely disordered personalities. Two axes (...) emerged reflecting a double-track pathway to fast strategy, based on restricted and unrestricted sociosexual strategies. When rotated, the fast–slow and sociosexuality axes turned out to be independent. Contrary to expectations, neither somatic effort—investment in status, material resources, social capital, and maintenance/survival—was aligned with reproductive effort, nor a clear tradeoff between current and future reproduction was evident. Finally, we examined the association of LH axes with seven high-order personality pathology traits: negative emotionality, impulsivity, antagonism, persistence-compulsivity, subordination, and psychoticism. Persistent and disinhibited subjects appeared as fast-restricted and fast-unrestricted strategists, respectively, whereas asocial subjects were slow strategists. Associations of LH traits with each other and with personality are far more complex than usually assumed in evolutionary psychology. (shrink)

Guided by principles of life history strategy development, this study tested the hypothesis that sexual precocity and violence are influenced by sensitivities to local environmental conditions. Two models of strategy development were compared: The first is based on indirect perception of ecological cues through family disruption and the second is based on both direct and indirect perception of ecological stressors. Results showed a moderate correlation between rates of violence and sexual precocity (r = 0.59). Although a model incorporating direct and (...) indirect effects provided a better fit than one based on family mediation alone, significant improvements were made by linking some ecological factors directly to behavior independently of strategy development. The models support the contention that violence and teenage pregnancy are part of an ecologically determined pattern of strategy development and suggest that while the family unit is critical in affecting behavior, individuals’ direct experiences of the environment are also important. (shrink)